package com.str.list;
public interface List {
// Each List value is a list (sequence) whose elements are objects.

// Modifiers
  public void clear();
  // Make this list empty.
  
  public void add(int i, Object val);
  // Add val as the element with index i in this list,
  // or do nothing if there can be no such element.

  public void add(Object val);
  // Add val after the last element of this list.

  public Object remove(int i);
  // Remove and return the element with index i in this list,
  // or return null if there is no such element.

// Accessors
  public boolean isEmpty();
  // Return true if and only if this list is empty.

  public int size();
  // Return this list's length.
  
  public Object getValue(int i);
  // Return the element with index i in this list,
  // or null if there is no such element.  
  
  public int indexOf(Object val);
  // Return the index of the specified val in this list, 
}
